Endoscopes are used in surgery to view internal portions of a patient's body, typically through a narrow incision in the body exterior. A typical flexible endoscope includes a long slender insertion section to be inserted into a body cavity of a patient, and an operation section coupled to a base end of the insertion section. The insertion section has a distal portion that incorporates an imaging unit. The endoscope also has one or more internal working channels through which a variety of instruments may be inserted.
The distal portion is attached to a bending portion that includes a plurality of annular joint elements connected in series, with adjacent joint elements pivotally joined together. Inside the joint pieces there are two pairs of operation wires: one for vertical turn and the other for horizontal turn. Pushing and pulling these operation wires leads the joint pieces to turn, and thereby the bending portion as a whole to bend in the vertical or horizontal direction. Endoscopes are typically only controlled in the XY orientation in the last 20 to 30 cm of length. The Z axis is controlled by linear movement of the endoscope from the operator. Pushing on a scope by the operator from the proximal end may not result in the desired linear motion of the distal tip due to looping or coiling of the scope along the way.
Existing endoscopes have a further shortcoming in that the endoscope needs a fulcrum to gain leverage to move tissue and properly apply tension and counter-tension with its accompanying tools. The location of where the fulcrum actually occurs along the length of the endoscope is highly variable and can lead to unpredictable motion or unsatisfactory control over the distal, working end of the endoscope and the associated instruments.
Other multiple element devices exist where each element is controlled via sets of wires or by pneumatic methods, electromechanical methods, length changing polymers, shape memory materials, or other generally linear methods of controlling the relative position of each element to the next element as well as the position of the lead element of the device. However, such existing devices utilize linear actuators and combinations of linear actuators and local locking mechanisms which limit the positioning capability to that of locking one element to the next in a fixed position.